There are lights which use a solid-state light source. Such lights produce white light by irradiating a phosphor layer containing phosphors with light emitted by the solid-state light source, and emit the white light. For example, in the case where the light is blue light, the phosphors cause yellow light resulting from excitation by one part of the blue light and the other part of the blue light that is transmitted to disperse; thus, the lights can produce white light obtained through the color mixing of these lights by irradiating the phosphor layer with the blue light emitted by the solid-state light source.
For example, Patent Literature (PTL 1) discloses an LED which emits white light from phosphors and a layered semiconductor structure which, as a solid-state light source, emits ultraviolet light. In PTL 1, using an epoxy or silicone resin containing phosphors, a phosphor layer is formed on one principal surface of a sapphire substrate on which the layered semiconductor structure has not been formed.